Isoquercitrin Attenuates Fatty Acid-Induced Hepatocyte Damage

Human HepG2 cells were purchased from American Type Culture Collection (Manassas, VA, USA). Cells were grown in Dulbecco’s modified Eagle’s medium (Gibco, Invitrogen, Carlsbad, CA, USA) containing 10% heat-inactivated fetal bovine serum (Hyclone, Logan, UT, USA) and 1% penicillin/streptomycin solution (Hyclone) at 37 °C in a humidified atmosphere of 5% CO₂. The medium was replaced every 2–3 days for all cell culture assays. Isoquercitrin (quercetin-3-O-β-d-glucopyranoside, ≥98% purity, #17793, Sigma-Aldrich, Inc., St. Louis, MO, USA) was treated to HepG2 cells for 6 h prior to FFA exposure, at the concentrations ranging from 1 to 50 μM which previously showed its lipid-lowering effect in rat primary hepatocytes by 24 h incubation without negative effects [16 (link)]. Cells were incubated with 0.5 mM FFA composed of oleic acid (#O7501, Sigma-Aldrich, Inc.) and palmitic acid (#P0007, Tokyo Chemical Industry Co. Ltd., Tokyo, Japan; 2:1) with or without Isoquercitrin (1–50 μM) co-treatment for 24 h, and samples were harvested for analysis.